The invention relates to a method and a device for the time-serial transmission of receive signals of electroacoustic transducers according to the preamble of claim 1.
A known circuit arrangement, also called an electronic module, for time-serial transmission of receive signals onto a data line or a bus (EP 0 689 188 B1) is assigned a respective transducer location of a spatially spread receive arrangement composed of a multiplicity of electroacoustic transducers, and connected at this location to the transducer and a synchronization line routed via all the transducer locations. The synchronization pulses transmitted on the synchronization line are generated by a master-clock generator. The frequency of the master-clock generator is specified by the sampling theorem for the receive signals in the highest receive frequency range, the multiplicity of transducer locations and a defined bit length for digitizing the receive signal at the output of the transducer. A clock generator of the circuit arrangement doubles the frequency of the master-clock generator and supplies clock pulses for digitizing and transmitting the digitized receive signals. In the interval between two sequential synchronization pulses, a timing pattern containing pattern pulses is generated by a counter from the clock pulses of the clock generator, and a gate is opened on a specific pattern pulse, and the digitized receive signal stored in a shift register of the circuit arrangement is transmitted onto the data line via the opened gate. Since within the timing pattern at each pattern pulse, a digitized signal as a data packet of a specific bit length is always switched onto the data line at one of the transducer locations, the timing pattern must be suitably designed to prevent the data packets overlapping. Tolerances in the components of the individual circuit arrangements at the transducer locations, e.g. in the propagation delay of the components, always result in the actual switching of the respective data packet being shifted with respect to the pattern pulse, which means that sufficiently large time gaps must be kept between the sequential data packets for error-free signal transmission. As a result, limits are set to the value of the clock frequency of the timing pattern, referred to below as the timing-pattern frequency, and to the data rate that can hence be transmitted on the data line. In order to transmit large volumes of data, a plurality of parallel data lines are used. Each data line performs the data transfer from a section of the transducer locations to the receive installation.
The object of the invention is to improve a method and a device of the type cited in the introduction so as to achieve a data transmission having a higher timing-pattern frequency and hence better utilization of the data line.